As shown in FIGS. 1 and 2, a typical van-type vehicle has a sliding side door. Upper and lower door tracks define a door path that guides the rear to front closing action and front to rear opening action of known sliding doors. The tracks are substantially straight over most of their length, causing the door to move essentially parallel to the body side over most of the door path. The tracks curve sharply inwardly at their respective ends defining a cinching portion of the door path. A center track may also be included to help guide the door during opening and closing.
A typical cable-type closer/opener drives the door through its fore and aft motion along the door path. The cinching portion of the door path causes the door to tilt inwardly in a final closing or cinching motion. As the door moves to its final closed position within a complementary vehicle door frame, the rear or trailing edge of the door tips inwardly and is then driven inward in a motion generally parallel to an inward-facing surface of a C pillar of the door frame. The rear edge continues to move inward along the cinching portion of the door path until an outer surface of the door and an outer surface of the body side panel are generally flush with one another and the door is latched in place.
The final closing action along the cinching portion of the door path typically involves less than an inch of travel. While the final closing motion along the cinching portion of the door path covers only a short distance, it's this final motion that both compresses a weather strip between the door and the frame and latches fork bolt type locks that mechanically hold the door in it's fully closed position. Consequently, the final cinching motion requires more force than what's required to slide the door fore and aft along the door path.
While some systems rely on the cable closer to provide the final closing or cinching force, many systems provide a separate and independent power cinching apparatus. Incorporation of a separate cinching apparatus allows the power opener/closer that moves the door fore and aft to be sized smaller.
Independent power cinchers typically include a powered fork bolt—a somewhat complex mechanism that requires electrical power to unlatch. Because known powered fork bolt cinchers require electrical power to unlatch they also require that a separate manual release be incorporated into the latch to, in the event of power failure, cause the latch to release and allow the door to be opened.
What is needed is a vehicle door cinching apparatus and method that doesn't require electrical power to release a door that has been cinched into its fully closed position.